The heat resistance, the fluidity, dimensional stability and the electrical characteristics of the liquid crystalline polyester may be improved by controlling the crystallinity of the liquid crystalline polyester according to the molecular structure and the production method. The demand of the liquid crystalline polyester has been expanded especially for small precision molded products in electrical and electronic applications. The liquid crystalline polyester, however, has high response to temperature during melting and may accordingly have the following problems: decrease of productivity due to a variation in resin metering time and a variation in injection peak pressure during injection molding; low strength of a small thin-wall molded product, such as low strength to insulator winding; and significant change before and after heating by the residual stress of the polymer itself and the residual stress during molding.
To solve such problems arising with respect to the liquid crystalline resins, for example, one proposed technique of improving the moldability decreases ΔS (entropy of melting) as the index representing the crystallinity of the liquid crystalline resin, to array the molecular chains of the liquid crystalline resin in a well-ordered state (see, for example, JP 2004-352862 A and JP 2006-089714 A). Another proposed technique increases ΔH (enthalpy of melting) as the index representing the degree of crystallinity, to enhance the characteristics such as chemical resistance and hydrolysis resistance of the liquid crystalline resin (see, for example, JP H08-134195 A. There is, on the other hand, a proposed technique of decreasing ΔH (enthalpy of melting) to improve the abrasion resistance of the fibers of the liquid crystalline resin (see, for example, JP 2010-248681 A).
The prior art techniques described above, however, still have a problem that the excessively low crystallinity causes insufficient strength of a small thin-wall molded product. On the other hand, the prior art techniques described above also have a problem that the excessively high crystallinity decreases the precision molding stability.
It could therefore be helpful to provide a liquid crystalline polyester having excellent precision molding stability such as a small variation in resin metering time and a small variation in injection peak pressure during injection molding, excellent dimensional stability under reflow and excellent strength of a small thin-walled molded product, as well as a production method of the same and a resin composition and a molded product obtained therefrom.